Answer:
Natalie would use a "test of difference between two means".
Step-by-step explanation:
First step: State the hypotheses of the test as follows;
Where are the Population means of years 1985 and 2015 respectively.
Second step: Determine the level of significance to be used for the testing. A 5% level of significance or 10% level of significance could be used.
Third step: Calculate the sample means and Variances for the two populations as follows;
where are the annual average high warmth for the years 1985 and 2015 respectively.
where are the respective sample variances for 1985 and 2015
and
Step three: The test statistic is computed as follows;
Step four: The Critical point for acceptance is calculated using the normal table and chosen level of significance. It is represented as
Step five: The decision rule is specified as follows:
Reject if , otherwise do not reject.
Step six: Conclusion is made based on the outcome of the test.
Note: used here represents "greater than"